Polishing fixture and method for fiber optic connectors

ABSTRACT

A polishing fixture and method suitable for use with springless fiber optic connectors, as well as connectors with integrated springs, is provided. The polishing fixture comprises at least a base plate and a plurality of connector assemblies. Each connector assembly includes a spring and the movement of the connector against the force of the spring applies a spring force to the connector during polishing to compensate for the variation of the protrusion of the connector and optical fiber below the base plate of the polishing fixture. The polishing fixture of this invention can be used with circular and non-circular shaped connectors and with single and multi-fiber connectors.

FIELD OF THE INVENTION

[0001] This invention relates to a polishing fixture for use with a polishing machine to secure fiber optic connectors to the fixture for high precision polishing operations. More specifically, this invention relates to a novel fixture for securing springless fiber optic connectors thereto for polishing operations.

BACKGROUND OF THE INVENTION

[0002] Fiber optic connectors are an important link in a fiber optic transmission system. Fiber optic connectors provide a mechanical link between two terminal ends of optical fibers thereby permitting transmission through the system. It is important that the connecting terminal ends of the optical fibers are polished to a high precision to minimize the attenuation of signal across the mechanical link.

[0003] Conventional fiber optic connectors typically have an integrated spring contained within the connector body. As used herein, the term “connector” includes numerous fiber optic connectors which may have a variety of ferrule configurations, including, for example, springless fiber optic connectors such as a simplified plug-and-jack SC and ST connector and MTRJ connectors. When such connectors are coupled to a conventional polishing fixture, the terminal ends of the optical fibers, which protrude through the holes formed in the ferrule, extend through the bottom of the polishing fixtures and are polished by a polishing machine. The springless conventional polishing fixture secures the connectors in a fixed position and relies on the connector's integrated spring to compensate for the variation in the protrusion of the ferrules and optical fibers during polishing.

[0004] Springless optical fiber connectors, however, cannot be adequately polished to a high precision using a conventional polishing fixture. Conventional polishing fixtures do not have springs to compensate for the variation in the protrusion of the ferrules and optical fibers. Hence, there remains a need in the art for a polishing fixture that can compensate for the variation in the protrusion of the ferrules and optical fibers in springless fiber optic connectors.

SUMMARY OF THE INVENTION

[0005] Accordingly, it is an object of this invention to provide a polishing fixture that can compensate for the variation in the protrusion of ferrules and optical fibers in fiber optic connectors.

[0006] Another object of the invention is to provide a polishing fixture that can compensate for the variation in the protrusion of optical fibers in springless fiber optic connectors.

[0007] Another object of the invention is to provide a spring load to the fiber optic connector during polishing.

[0008] These and other objects of this invention are realized by a polishing fixture comprising a base plate having at least one puck assembly disposed thereon. The puck assembly comprises a connector receptacle attached to the base plate wherein the connector receptacle is adapted to receive a fiber optic connector for polishing. The puck assembly also includes a spring to bias the fiber optic connector during polishing.

[0009] In an embodiment, the connector receptacle is fixedly attached to the base plate. In another embodiment, the connector receptacle is movably attached to the base plate. In accordance with one aspect of the invention, the fiber optic connector is substantially fixed to the connector receptacle during polishing, and both the connector and the receptacle are biased toward the base plate of the polishing fixture. The fiber optic connector may be affixed to the connector receptacle during polishing by any known means, including, for example, a bayonet mount or snap fitting spring arms. The connector receptacle may be received in a spring housing, which may be directly affixed to the base plate. Furthermore, the biasing spring may be disposed on the outside or the inside of the connector receptacle.

[0010] In accordance with another aspect of the invention, the fiber optic connector is movable relative to the connector receptacle. The spring preferably exerts a biasing force to bias the connector receptacle towards the base plate.

[0011] Preferably, the connector receptacle is directly affixed to the base plate. The spring may form a component of a spring plate assembly to exert the biasing force. On the other hand, the spring may be a cantilever or leaf spring positioned above the fiber optic connector to exert the biasing force.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings form a part of the specification and are to be read in conjunction with the specification, in which like reference numerals are used to indicate like parts in the various views:

[0013]FIG. 1 is an elevated view of an embodiment of a polishing fixture in accordance to this invention with a plurality of fiber optic connectors coupled thereto;

[0014]FIG. 2 is a partially exploded view of the polishing fixture of FIG. 1;

[0015]FIG. 3 is an enlarged elevational view of a plug-and-jack puck assembly of the polishing fixture of FIG. 1;

[0016]FIG. 4 is a cross-sectional view of the plug-and-jack puck assembly of FIG. 3 along line 4-4;

[0017]FIG. 5 is an exploded view of the plug-and-jack puck assembly of FIG. 3;

[0018]FIG. 6 is a partially exploded elevational view of another embodiment of the polishing fixture in accordance to this invention;

[0019]FIG. 7 is an enlarged view of the plug-and-jack puck assembly shown in FIG. 6;

[0020]FIG. 8 is a top view of the polishing fixture of FIG. 6;

[0021]FIG. 9 is a cross-sectional view of the polishing fixture of FIGS. 6 and 8 along line 9-9;

[0022]FIG. 10 is an elevational view of another embodiment of the polishing fixture in accordance to this invention;

[0023]FIG. 11 is an exploded view of the polishing fixture of FIG. 10;

[0024]FIG. 12 is another embodiment of a puck assembly in accordance to this invention;

[0025]FIG. 13 is an exploded view of the puck assembly of FIG. 12;

[0026]FIG. 14 is a cross-sectional view of the puck assembly of FIG. 12; and

[0027]FIG. 15 is a polishing fixture adapted to receive a plurality of the puck assembly of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION

[0028] As shown generally in FIGS. 1-5, where like numbers designate like parts, reference number 10 designates an embodiment of the polishing fixture in accordance with this invention. Polishing fixture 10 is adapted to have a number of plug-and-jack puck assemblies 12 fixedly mounted thereon. Although twelve puck assemblies 12 are illustrated in FIGS. 1 and 2, any number of puck assemblies 12 can be mounted on the polishing fixture 10. Polishing fixture 10 comprises a substantially circular base plate 14 and a hollow arm or central boss 16. As more specifically shown in FIGS. 3-5, each plug-and-jack puck assembly 12 is adapted to releasably receive a fiber optic connector 18. Although springless connectors 18 are shown in the accompanying drawings, the polishing fixtures 10 described herein are also suitable for use with connectors having an integrated spring. Thus, this invention is not limited to any specific connectors described and illustrated herein. Puck assembly 12 comprises a spring housing 20, which is preferably fixedly attached to base plate 14 of polishing fixture 10, connector receptacle 22, compression spring 24, and retainer housing 26. Connector receptacle 22 has a tubular body 28 with bayonet slots 30 defined thereon and shoulder 32. Spring housing 20 is sized and dimensioned to receive connector receptacle 22. Preferably, spring housing 20 comprises substantially flat, internal surfaces 34, which are adapted to match with corresponding flat surfaces 36 of shoulder 32 of connector receptacle 22. Substantially flat surfaces 34 and 36 cooperate to minimize rotational movement of the connectors 18 during polishing.

[0029] Connector 18 preferably has two bayonet lugs 38 disposed thereon. Lugs 38 are sized and dimensioned to be lockably received in bayonet slots 30 of connector receptacle 22, such that there is no or minimal relative motion between connector 18 and connector receptacle 22. As particularly shown in FIG. 4, after the connector 18 is inserted through connector receptacle 22, terminal portion 40 of connector 18 is further inserted through well 42 of the spring housing 20 and extends therethrough, such that a portion of terminal portion 40 protrudes through the bottom of spring housing 20 and base 14 and is exposed for polishing. Terminal portion 40 defines a channel 44 that contains the terminal end of the optical fiber 46 for polishing.

[0030] Compression spring 24 is disposed in the annular space between tubular body 28 of connector receptacle 22 and is partially compressed between shoulder 32 of connector receptacle 22 and a top portion of retainer housing 26. Retainer housing 26 is coupled to the spring housing 20 by matching threads shown most clearly in FIGS. 4 and 5. After the plug-and-jack puck assembly 12 is assembled, a portion of the connector receptacle 22 including bayonet slots 30 extends through the hole on top of retainer housing 26 to readily receive connector 18. After fiber optic connector 18 is inserted in the connector receptacle 22, terminal portion 40 of connector 18, with optical fiber 46 disposed therethrough, protrudes through the bottom of the spring housing 20 and extends below the bottom of the base plate 14 of the polishing fixture 10.

[0031] Although not shown in the figures, the polishing fixture is mounted to a rotary polishing machine. Typically, arm or boss 16 is mounted to an axle or spindle of the polishing machine and is fixedly connected to the machine, for example, by a swing-arm on the machine. Other types of attachments for the polishing machine, such as, for example, the polishing apparatus shown in U.S. Pat. No. 5,720,653, are also suitable for use with this invention. In an embodiment, the protruded portion of the connector 18 with the optical fiber 46 rest on an electrically driven platen that extends up from the base of the polishing machine, and a downward force is applied to displace the connector 18 with the optical fiber 46 upward. This upward displacement causes the spring 24 to compress. Preferably, this displacement applies a spring load of about two pounds, simulating a desirable spring force exerted by an integrated spring of a conventional connector. The protruded portions of the connectors 18 and optical fiber 46 are then effectively polished when the platen is driven by the polishing machine. In an embodiment of this invention, the platen is driven by the polishing machine in a circular pattern. In another embodiment of this invention, the platen is driven by the polishing machine in a non-circular pattern.

[0032] Furthermore, if a protruded portion of the terminal end 40 of the fiber optic connector 18 over-extends below the bottom of the polishing fixture 10, the platen pushes the overextended portion upward in the direction of arrow 48 in FIG. 4 against the force of spring 24. Hence, the protruded portions of all connectors 18 mounted on the polishing fixture are substantially at the same height before polishing begins, and polishing is carried out uniformly over all the mounted connectors 18. Additionally, the polishing fixture of this invention is suitable for use with conventional connectors with integrated springs. In this situation, either spring 24 in puck assembly 12 or an integrated spring inside the conventional connector or both may be compressed.

[0033] FIGS. 6-9 illustrate another embodiment of the polishing assembly in accordance with this invention. Polishing fixture 50 is shown with a number of plug-and-jack puck assemblies 52 coupled thereto. Three puck assemblies 52 are shown wherein exploded views in various stages. A significant feature of this embodiment is that connector 18 is movable relative to the connector receptacle 54. Furthermore, connector receptacle 54 is fixedly connected directly to the base plate 14. As more particularly shown in FIG. 9, connector receptacle 54 has a tubular body 56 defining a pair of vertical slots 58 adapted to receive bayonet lugs 38 on connector 18. Slots 58 allow the bayonet lugs 38 and connector 18 to be movable in the vertical direction within the slots. A spring plate assembly 60 is positioned above the connector 18 to exert a spring force on connector 18 during polishing and to compensate for the variation in the protrusion of the connector and optical fiber.

[0034] Spring plate assembly 60 includes plate 62, a plurality of compression springs 64, a corresponding number of bolts 66, and an enclosing cap 68. As best shown in FIG. 7, bolts 66 are inserted through the top of cap 68 through pre-drilled holes and are then inserted through the corresponding springs 64 and are threaded through the threaded holes on plate 62. Due to the smooth upper portions of bolts 66, plate 62 is movable in the direction of arrow 70, shown in FIG. 9, against the force of springs 64.

[0035] Connector 18 is inserted into body 56 of connector receptacle 54 such that lugs 38 are movably received in vertical slots 58 and terminal portion 40 extends through the bottom channel on the connector receptacle 54 and protrudes below base plate 14, as described above. Spring plate assembly 60 is then coupled with connector receptacle 54 by means of the corresponding threads, as shown. Thereafter, connector 18 abuts plate 62 and spring plate assembly 60 exerts a force on connector 18. Plate 62 and bolts 66 are movable in the direction of arrow 70 to exert a spring force on connector 18 and to compensate for the variation of the protrusion by connector 18 through base plate 14.

[0036]FIGS. 10 and 11 show another embodiment in accordance with this invention. Similar to polishing fixture 50, polishing fixture 72 has base plate 14 and a plurality of connector receptacles 54 with vertical slots 58. Connectors 18 are inserted into connector receptacles 54 such that the connectors and the connector receptacles are movable relative to each other. Thereafter, clip ring 74 is placed over central boss 100, such that each cantilever arm 76 is positioned above each connector 18. Nut 78 is threaded over boss 100 to press clip ring 74 downward such that each cantilever arm 76 acts like a leaf spring to exert a spring force on each connector 18. Connectors 18 are also movable upward against the spring force of arms 76 to compensate for the variation in the protrusion of ferrules 18 with optical fibers 46.

[0037] FIGS. 12-15 represent another embodiment in accordance to this invention. Puck assembly 80 is sized and dimensioned to accept a non-circular connector 82. In this 30 embodiment, connector 82 is illustrated as a square-profiled connector. Non-circular connector 82, however, many have any polygonal, elliptical, or other profile. Similar to the puck assembly 12 described above and shown in FIGS. 1-5, connector 82 and the connector receptacle are fixedly attached to each other, i.e., they are not movable relative to each other, during polishing. As most clearly shown in FIGS. 13 and 14, puck assembly 80 comprises base 84, connector receptacle 86, compression spring 88, and nut 90.

[0038] Base 84, which performs the same function as the spring housing 20 of polishing fixture 10, is fixedly attached to base plate 92, shown in FIG. 15. Connector receptacle 86 defines a hole through its bottom surface and is adapted to fit over boss 94 of base 84. Spring 88 is positioned over boss 94 and nut 90 is fixedly fitted, for example by press fitting, to the top of boss 94 to contain spring 88 between nut 90 and connector receptacle 86 as best shown in FIG. 14. Connector receptacle 86 is sized and configured to be movable in the direction of arrow 96 relative to base 84, against the force of spring 88.

[0039] Adapter has cavity 96 adapted to receive connector 82, such that the connector is fixed to the adapter and both of these components are movable relative to base 84. Connector 82 has two spring prongs 98, which snap into cavity 96 to secure connector 82 to connector receptacle 86. In this embodiment, the movement of connector 82 and connector receptacle 86 against the force of spring 88 and relative to base 84 exerts a spring force on the connector during polishing and compensates for the variation of the protrusion of the connectors 82 below the base plate 92.

[0040] While various embodiments have been described in fulfillment of the features, aspects, and advantages of this invention, it is understood that these embodiments can be used singly or in combination thereof. For example, although single fiber connectors are illustrated herein, MT or other multi-fiber ferrules or connectors can be used with this invention. Additionally, the invented polishing fixture can be adapted to accept any number of ferrules or connectors. Furthermore, the puck assemblies described above can be adapted to be used with linear, oval, or rectangular polishing fixtures in addition to circular fixtures. It should be recognized that these embodiments are merely illustrative of this invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of this invention. 

What is claimed is:
 1. A polishing fixture comprising: a base plate for securing a puck assembly thereto; the puck assembly configured to engage a fiber optic connector, the puck assembly comprises: a connector receptacle for receiving the fiber optic connector for polishing, wherein the connector receptacle is attached to the base plate; and a spring for providing a biasing force to the fiber optic connector during polishing.
 2. The polishing fixture of claim 1, wherein the puck assembly further comprises: means for substantially eliminating the relative motion between the connector receptacle and the fiber optic connector.
 3. The polishing fixture of claim 2, wherein the means for substantially eliminating the relative motion between the connector receptacle and the fiber optic connector comprises: at least one bayonet lug, wherein the bayonet lug is sized and dimensioned to be lockably received in a bayonet slot on the connector receptacle.
 4. The polishing fixture of claim 1, wherein the fiber optic connector engages the connector receptacle using a bayonet connection.
 5. The polishing fixture of claim 1, wherein the fiber optic connector engages the connector receptacle using one or more snap fitting spring arms.
 6. The polishing fixture of claim 1, wherein the spring biases the connector receptacle towards the base plate.
 7. The polishing fixture of claim 1, wherein the puck assembly further comprises: a spring housing to secure the spring, wherein the spring housing is fixedly attached to the base plate.
 8. The polishing fixture of claim 1, wherein the spring is disposed around the connector receptacle.
 9. The polishing fixture of claim 1, wherein the spring is disposed inside the connector receptacle.
 10. The polishing fixture of claim 7, wherein the connector receptacle and the spring housing each comprise substantially corresponding straight edges to substantially eliminate relative rotational movement of the fiber optic connector during polishing.
 11. The polishing fixture of claim 1, wherein the connector receptacle is movable relative to the fiber optic connector.
 12. The polishing fixture of claim 11, wherein the polishing fixture further comprises: a spring plate assembly for use with the spring to exert the biasing force on the fiber optic connector during polishing and to compensate for the variation in the protrusion of the fiber optic connector and an optical fiber.
 13. The polishing fixture of claim 12, wherein the spring plate assembly comprises a plate, a plurality of compression springs, a plurality of bolts corresponding to an equal number of the compression springs, and an enclosing cap.
 14. The polishing fixture of claim 13, wherein the plate is biased by the spring to exert the biasing force.
 15. The polishing fixture of claim 12, wherein the polishing fixture further comprises: a clip ring having at least one cantilever arm for use with the spring plate assembly, wherein the cantilever arm exerts a spring force on the fiber optic connector.
 16. The polishing fixture of claim 15, wherein the fiber optic connector is positioned between the cantilever arm and the connector receptacle.
 17. A polishing fixture comprising: a base plate for securing a puck assembly thereto; the puck assembly configured to engage a fiber optic connector, the puck assembly comprises: a connector receptacle for receiving the fiber optic connector for polishing; and a spring for providing a biasing force to the fiber optic connector during polishing.
 18. A puck assembly attachable to a polishing fixture, the puck assembly comprises: a connector receptacle adapted to receive a fiber optic connector to polish; and a spring to bias the fiber optic connector during polishing..
 19. The puck assembly of claim 18, wherein the puck assembly further comprises: means for substantially eliminating the relative motion between the connector receptacle and the fiber optic connector.
 20. The puck assembly of claim 19, wherein the means for substantially eliminating the relative motion between the connector receptacle and the fiber optic connector comprises: at least one bayonet lug, wherein the bayonet lug is sized and dimensioned to be lockably received in a bayonet slot on the connector receptacle.
 21. The puck assembly of claim 20, wherein the connector receptacle is movable relative to the fiber optic connector.
 22. A method of using a polishing fixture to compensate for the variation in the protrusion of one or more springless fiber optic connectors, comprising: providing a puck assembly puck configured to engage the fiber optic connector; securing the puck assembly to a base plate; engaging the springless fiber optic connector in the puck assembly, wherein the puck assembly comprises: a connector receptacle for receiving the fiber optic connector for polishing, wherein the connector receptacle is attached to the base plate; and a spring for providing a biasing force to the fiber optic connector during polishing. applying a downward force to the polishing fixture to displace the springless fiber optic connector; and polishing the terminal end of the fiber optic connector. 